1 files changed, 28 insertions, 0 deletions
diff --git a/media/video/capture/screen/differ_block.h b/media/video/capture/screen/differ_block.h
new file mode 100644
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--- /dev/null
+++ b/media/video/capture/screen/differ_block.h
@@ -0,0 +1,28 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_VIDEO_CAPTURE_SCREEN_DIFFER_BLOCK_H_
+#define MEDIA_VIDEO_CAPTURE_SCREEN_DIFFER_BLOCK_H_
+
+#include "base/basictypes.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+// Size (in pixels) of each square block used for diffing. This must be a
+// multiple of sizeof(uint64)/8.
+const int kBlockSize = 32;
+
+// Format: BGRA 32 bit.
+const int kBytesPerPixel = 4;
+
+// Low level functions to compare 2 blocks of pixels. Zero means the blocks
+// are identical. One - the blocks are different.
+MEDIA_EXPORT int BlockDifference(const uint8* image1,
+                                 const uint8* image2,
+                                 int stride);
+
+}  // namespace media
+
+#endif  // MEDIA_VIDEO_CAPTURE_SCREEN_DIFFER_BLOCK_H_